/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the 
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigoths@visigoths.org.
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.core;

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Logger;

import com.googlecode.cswish.util.bean.ModelUtil;

import freemarker.ext.beans.BeansWrapper;
import freemarker.ext.beans.StringModel;
import freemarker.template.TemplateException;
import freemarker.template.TemplateHashModel;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;

/**
 * Enhance &lt;nested> tag to support 'inject' parameter, grammar: &lt;nested inject var><p>
 * 
 * Inject the properties of 'var' to the macro input parameter of the &lt;nested> tag body<p>
 * 
 * An instruction that processes the nested block within a macro instruction.
 * @author <a href="mailto:jon@revusky.com">Jonathan Revusky</a>
 */
final class BodyInstruction extends TemplateElement {
    
	private final static Logger logger = Logger.getLogger(BodyInstruction.class);
    
    private List bodyParameters;
    
    
    private static Field unifiedCallArgs;
    static {
    	try {
			unifiedCallArgs = UnifiedCall.class.getDeclaredField("namedArgs");
			unifiedCallArgs.setAccessible(true);
		} catch (Exception ex) {
			logger.error("Failed to find field: namedArgs", ex);
		}
    }
    
    BodyInstruction(List bodyParameters) {
        this.bodyParameters = bodyParameters;
    }
    
    List getBodyParameters() {
        return bodyParameters;
    }

    /**
     * There is actually a subtle but essential point in the code below.
     * A macro operates in the context in which it is defined. However, 
     * a nested block within a macro instruction is defined in the 
     * context in which the macro was invoked. So, we actually need to
     * temporarily switch the namespace and macro context back to
     * what it was before macro invocation to implement this properly.
     * I (JR) realized this thanks to some incisive comments from Daniel Dekany.
     */
    void accept(Environment env) throws IOException, TemplateException {
        Context bodyContext = new Context(env);
        
        // inject the parameter
        if (bodyParameters != null && bodyParameters.size() >= 1) {
        	String cmd = bodyParameters.get(0).toString();
        	if ("inject".equals(cmd)) {
        		TemplateElement body = bodyContext.invokingMacroContext.body;
        		if (body instanceof MixedContent) {
        			MixedContent mixedContent = (MixedContent) body;
        			for (Object element : mixedContent.nestedElements) {
        				if (element instanceof UnifiedCall) {
        					injectArgument(env, (UnifiedCall) element);
        				}
        			}
        		} else {
        			if (body instanceof UnifiedCall) {
        				injectArgument(env, (UnifiedCall) body);
        			}
        		}
        	} else if ("assign".equals(cmd)) {
        		// see freemarker.core.Assignment
        		String toVariableName = bodyParameters.get(1).toString();
        		String fromVariableName = bodyParameters.get(2).toString();
        		TemplateModel variable = env.getVariable(toVariableName);
        		String strVariable = variable.toString();
        		TemplateModel value = env.getVariable(fromVariableName);
        		env.setVariable(strVariable, value);
        		return ;
        	}
        }
        
        env.visit(bodyContext);
    }

	private void injectArgument(Environment env, UnifiedCall unifiedCall) {
		try {
			Object injectModelName = bodyParameters.get(1);
			Object injectModel = env.getVariable(injectModelName.toString());
			if (injectModel != null) {
				String desc = unifiedCall.getDescription();
				String nameExp = desc.substring(desc.indexOf(' ') + 1);
				TemplateModel tm = env.getVariable(nameExp);
				if (tm instanceof Macro) {
					Macro macro = (Macro) tm;
					// nameArgs is the runtime arguments, such as Macro 'text' contains 'name','label' etc
					Map nameArgs = (Map) unifiedCallArgs.get(unifiedCall);
					if (nameArgs == null) {
						nameArgs = new HashMap<String, Object>();
						unifiedCallArgs.set(unifiedCall, nameArgs);
					}
					
					BeansWrapper wrapper = (BeansWrapper) env.getObjectWrapper();
					for (String argumentName : macro.getArgumentNames()) {
						// TODO: override the default value? ==> !nameArgs.containsKey(argumentName) 
						// inject the new value as default value
						Object value = getProperty(injectModel, argumentName);
						if (value != null) {
							Identifier identifier = new Identifier(argumentName);
							nameArgs.put(argumentName, identifier);
							env.setVariable(argumentName, new StringModel(value, wrapper));
						}
					}
				}
			}
		} catch (Exception ex) {
			logger.error("Failed to get field value: namedArgs", ex);
		}
		
	}
	
	private Object getProperty(Object model, String property) {
		Object value;
		if (model instanceof TemplateModel) {
			if (model instanceof TemplateHashModel) {
				TemplateHashModel hashModel = (TemplateHashModel) model;
				try {
					value = hashModel.get(property);
				} catch (TemplateModelException ex) {
					value = null;
					logger.error("Failed to get property:" + property, ex);
				}
			} else {
				value = null;
			}
		} else {
			value = ModelUtil.getSimpleProperty(model, property);
		}
		
		// TODO: convert the value to Expression
		
		return value;
	}

    public String getCanonicalForm() {
        StringBuffer buf = new StringBuffer("<#nested");
        if (bodyParameters != null) {
            for (int i = 0; i<bodyParameters.size(); i++) {
                buf.append(' ');
                buf.append(bodyParameters.get(i));
            }
        }
        buf.append('>');
        return buf.toString();
    }

    public String getDescription() {
        return "nested macro content";
    }

/*
    boolean heedsOpeningWhitespace() {
        return true;
    }

    boolean heedsTrailingWhitespace() {
        return true;
    }
*/
    class Context implements LocalContext {
        Macro.Context invokingMacroContext;
        Environment.Namespace bodyVars;
        
        Context(Environment env) throws TemplateException {
            invokingMacroContext = env.getCurrentMacroContext();
            List bodyParameterNames = invokingMacroContext.bodyParameterNames;
            if (bodyParameters != null) {
                for (int i=0; i<bodyParameters.size(); i++) {
                    Expression exp = (Expression) bodyParameters.get(i);
                    TemplateModel tm = exp.getAsTemplateModel(env);
                    if (bodyParameterNames != null && i < bodyParameterNames.size()) {
                        String bodyParameterName = (String) bodyParameterNames.get(i);
                        if (bodyVars == null) {
                            bodyVars = env.new Namespace();
                        }
                        bodyVars.put(bodyParameterName, tm);
                    }
                }
            }
        }
        
        public TemplateModel getLocalVariable(String name) throws TemplateModelException {
            return bodyVars == null ? null : bodyVars.get(name);
        }
        
        public Collection getLocalVariableNames() {
            List bodyParameterNames = invokingMacroContext.bodyParameterNames;
            return bodyParameterNames == null ? Collections.EMPTY_LIST : bodyParameterNames;
        }
    }
}
